How can I filter by specific date from realm object in swift? - swift

Question

I have a realm object with date property type of Date , and want to get list of items with specific date.
If I click specific date from calendar, for example 2020-03-06 , then it will present list of items which was created in 2020-03-06.
:: EDITED ::
Here is my realm object named "Profile" and there are dates from
2020-03-05 to 2020-03-08 .
Here is my Profile object and ProfileManager Singleton.
class Profile: Object {
#objc dynamic var date: Date!
#objc dynamic var content: String!
convenience init(_ content: String) {
self.init()
self.content = content
self.date = Date()
}
}
class ProfileManager {
static let shared = ProfileManager()
private var realm = try! Realm()
var profileList: Results<Profile>?
private init() {
profileList = realm.objects(Profile.self)
}
func save(_ object: Profile) {
do {
try realm.write {
realm.add(object)
}
} catch {
print(error)
}
}
func addNewProfile(_ content: String) {
let newProfile = Profile(content)
save(newProfile)
}
}
And lastly, here is a viewController which has to buttons. One for
adding new Profile, and one for printing filtered profile list.
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func addProfilePressed(_ sender: Any) {
ProfileManager.shared.addNewProfile("profile content")
}
#IBAction func filterButtonPressed(_ sender: Any) {
let stringDate = "2020-03-09"
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
let searchDate:Date = dateFormatter.date(from: stringDate)!
let results = ProfileManager.shared.profileList!.filter("date == %#", searchDate)
print(searchDate)
print(results)
for profile in results {
print(profile.content!)
}
}
}
the result on the console, when filterButtonPressed method called.
2020-03-08 15:00:00 +0000
Results<Profile> <0x7f9b36f160a0> (
)
How can I fix this problem?
And here is another problem.
I set to 'stringDate' a value of "2020-03-09"
but when I print converted date 'searchDate' , it prints "2020-03-08"
why this happens?
Hope now my questions is more clear to understand.

Answer 1

My original answer is below which, after a lot of research was only somewhat correct.
The actual answer has to do with the timestamp portion of the date.
So... if we create a date object using the below code and set it to a known date,
let stringDate = "2020-03-08"
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
let searchDate:Date = dateFormatter.date(from: stringDate)!
the actual object will look like this
2020-03-08T05:00:00.000Z
However, how the Profile object is being created is like this
convenience init(_ content: String) {
self.init()
self.content = content
self.date = Date()
}
and that date object looks like this
2020-03-08T16:10:25.123Z
so as you can see, if we filter for a specific date these are not equal
2020-03-08T05:00:00.000Z != 2020-03-08T16:10:25.123Z
which is why this
let stringDate = "2020-03-08"
let searchDate:Date = dateFormatter.date(from: stringDate)!
let searchResults = realm.objects(Profile.self).filter("date == %#", searchDate)
could not find the date because it's filtering for this
2020-03-08T05:00:00.000Z
To fix, change the profile class with a date stamp with a default time stamp
class Profile: Object {
#objc dynamic var date: Date!
#objc dynamic var content: String!
convenience init(_ content: String) {
self.init()
self.content = content
let formatter = DateFormatter()
formatter.timeStyle = .none
formatter.dateFormat = "MM/dd/yy"
let today = Date()
let s = formatter.string(from: today)
let d = formatter.date(from: s)
self.date = d
}
}
or, store your dates as a string yyyymmdd which will remove the ambiguity completely.
-- ORIGINAL ANSWER BELOW ---
Filtering by date is fully supported on date objects. Here's two quick examples. One for filtering for a specific date (for your question) and one for a date range using BETWEEN.
Note, I have a function makeDate that casts a string to a date object. This example uses a Realm DogClass object that has a dog_birthdate Date property.
This filters for objects with a specific date
let searchDate = self.makeDate(fromString: "06/01/2019")
let specificDateResults = realm.objects(DogClass.self)
.filter("dog_birthdate == %#", searchDate)
for dog in specificDateResults {
print(dog.dog_name)
}
This filters for objects within a date range
let startDate = self.makeDate(fromString: "06/01/2019")
let endDate = self.makeDate(fromString: "06/20/2019")
let dateRangeResuls = realm.objects(DogClass.self)
.filter("dog_birthdate BETWEEN {%#,%#}", startDate, endDate)
for dog in dateRangeResuls {
print(dog.dog_name)
}
EDIT: Using the code in the comment from the OP for testing
let stringDate = "2019-06-01"
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
let searchDate:Date = dateFormatter.date(from: stringDate)!
let result = realm.objects(DogClass.self).filter("dog_birthdate == %#", searchDate)
for dog in result {
print(dog.dog_name)
}
which works perfectly.